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Global surveillance of SARS-CoV2 variants has detected an increase in strains from different countries, the World Health Organization said in its weekly epidemiological update. The double mutant Indian variant (B.1.617) has been reported from at least 17 countries.
“As of April 27, over 1,200 sequences have been uploaded onto Gisaid (Global Initiative on Sharing All Influenza Data) and assigned to lineage B.1.617 (collectively) from at least 17 countries; most sequences were uploaded from India, the UK, the US and Singapore,” it added. India accounted for 38 per cent of global Covid-19 cases reported the previous week.
Sub-lineages
The WHO further pointed out that the lineage of the variant “comprises several sub-lineages, including B.1.617.1, B.1.617.2 and B.1.617.3, which slightly differ by their characteristic mutations.”
Both B.1.617.1 and B.1.617.2 were first identified in India in December, and have been detected increasingly in lone with the major surge in case in the country. B.1.617.3 was first detected in India in October 2020, but relatively fewer viruses matching this sub-lineage have been reported to date.
B.1.617 includes several mutations present in other VOIs (variants of interest) and VOCs (variants of concern), the WHO said. “Three characteristic mutations of this variant include L452R, P681R, and E484Q...”
The L452R, identified in another VOI, has been associated with increased transmissibility, a reduction in neutralisation by some (but not all) monoclonal antibody treatments, and a moderate reduction in neutralisation in post-vaccination sera in the US, the WHO said.
Higher growth rate
In India, the geographical distribution of B.1.617 is observed across regions, with co-circulation of other variants that collectively may be playing a role in the current surge, it added.
Studies show that the B.1.617 has a higher growth rate than the other circulating variants in India, suggesting potential increased transmissibility, with other co-circulating variants also demonstrating increased transmissibility. “Other drivers may include challenges around the implementation and adherence to public health and social measures (PHSM), and social gatherings (including mass gatherings during cultural and religious celebrations, and elections),” the WHO said.
Pointing out that further investigation was needed to understand the relative contribution of these factors, the WHO said, “virus evolution is expected and the more SARS-CoV-2 circulates, the more opportunities it has to mutate.”
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